From patchwork Tue Apr 26 16:43:03 2022 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Alexander Potapenko X-Patchwork-Id: 12827517 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1221CC433F5 for ; Tue, 26 Apr 2022 16:45:51 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 9CB296B00A3; Tue, 26 Apr 2022 12:45:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 9A46D6B00A4; Tue, 26 Apr 2022 12:45:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 844B06B00A5; Tue, 26 Apr 2022 12:45:50 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (relay.a.hostedemail.com [64.99.140.24]) by kanga.kvack.org (Postfix) with ESMTP id 74D056B00A3 for ; Tue, 26 Apr 2022 12:45:50 -0400 (EDT) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay08.hostedemail.com (Postfix) with ESMTP id 4AAED20CF2 for ; Tue, 26 Apr 2022 16:45:50 +0000 (UTC) X-FDA: 79399606860.10.19C5DF5 Received: from mail-wr1-f74.google.com (mail-wr1-f74.google.com [209.85.221.74]) by imf11.hostedemail.com (Postfix) with ESMTP id 21F4E4004C for ; Tue, 26 Apr 2022 16:45:46 +0000 (UTC) Received: by mail-wr1-f74.google.com with SMTP id s8-20020adf9788000000b0020adb01dc25so2047659wrb.20 for ; Tue, 26 Apr 2022 09:45:49 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20210112; h=date:in-reply-to:message-id:mime-version:references:subject:from:to :cc; bh=KHDnEJZlYbtguNecmw4Z0aoQP18cjcWXna880BlF2jg=; b=Ras6zX6zLyLhsIDtzjqqN9y4Bp5f6rPNvg/NlhbZeOJcSZ0W0h6WszebH9Jl+tDnIj 1d8SC1JokEP9rj0/Uz/B0C8vgBdM75W2cOctkHAhkLUnzcLWel+aJ8n1Z2d27uToZyPD NXcsYuwWmfXUsoUSNdeFpNkCp8Mdmw2X2PM8Z0Xq3w/pvHZee2tgfSDClqP6w/GG0G6Z Mkg5MkTefNZEIo51rh3WSUC/xRWyYaKD3+5kRfKXRqTWJTGdKD34V/dogH3TIl3qdspb r/9R17wsy7X98UcL39rrXIx8RR/Zx48ZWvJVe4g3RHHZ1p7AGTIwvBiDniEVZixdJ1br ihtw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=x-gm-message-state:date:in-reply-to:message-id:mime-version :references:subject:from:to:cc; bh=KHDnEJZlYbtguNecmw4Z0aoQP18cjcWXna880BlF2jg=; b=FrwKYRSlnXVBRD57HD3b5dOe3hfyKU0LN3L8z5qcWJ84WYCOz35vh69XIiwUvxH6qs sJlv3BCFqstwIIB68RnuE3QpgLfmYwP3s6LnzdwDFqDy290c41tnN+4mVfjkvjgjkpcq ggAxW4Q3RFFr/59tq/IzgMvZsCgswItaXJBo4I0/fDekzVYHuL1BSweDYOD6t6UN2gbp 1gFBIwmkdHYPxQYadjI1CuXAXj+XRrU/SUy7F+5oVtVRN+WbVLXUJUsH+DyVJcGaH3BY SyDToRwrlhbxbGh1cXniJIUHnLqZMoQ2Kqs6vYBMwJiLFcDZm2tI7JqgdhjeF40mnELE AZuw== X-Gm-Message-State: AOAM53144e4tSiO9ELF/xS0vAHctQnLRKEyZ0UVwQRcaZc70/IZuqUF9 h4XT8aiBA1t5ZUT7KFs/pfU021w6JIQ= X-Google-Smtp-Source: ABdhPJwEbc2ldIDEpaUEaYnMNUbLZOo12zW9lcP4NsRCoKnifcBnuhUmGJEZqd7cMdPo2nqMrlaeyXx5FlQ= X-Received: from glider.muc.corp.google.com ([2a00:79e0:15:13:d580:abeb:bf6d:5726]) (user=glider job=sendgmr) by 2002:adf:e289:0:b0:1e3:14ad:75fe with SMTP id v9-20020adfe289000000b001e314ad75femr18987161wri.685.1650991548482; Tue, 26 Apr 2022 09:45:48 -0700 (PDT) Date: Tue, 26 Apr 2022 18:43:03 +0200 In-Reply-To: <20220426164315.625149-1-glider@google.com> Message-Id: <20220426164315.625149-35-glider@google.com> Mime-Version: 1.0 References: <20220426164315.625149-1-glider@google.com> X-Mailer: git-send-email 2.36.0.rc2.479.g8af0fa9b8e-goog Subject: [PATCH v3 34/46] kmsan: kcov: unpoison area->list in kcov_remote_area_put() From: Alexander Potapenko To: glider@google.com Cc: Alexander Viro , Andrew Morton , Andrey Konovalov , Andy Lutomirski , Arnd Bergmann , Borislav Petkov , Christoph Hellwig , Christoph Lameter , David Rientjes , Dmitry Vyukov , Eric Dumazet , Greg Kroah-Hartman , Herbert Xu , Ilya Leoshkevich , Ingo Molnar , Jens Axboe , Joonsoo Kim , Kees Cook , Marco Elver , Mark Rutland , Matthew Wilcox , "Michael S. Tsirkin" , Pekka Enberg , Peter Zijlstra , Petr Mladek , Steven Rostedt , Thomas Gleixner , Vasily Gorbik , Vegard Nossum , Vlastimil Babka , kasan-dev@googlegroups.com, linux-mm@kvack.org, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 21F4E4004C X-Stat-Signature: fniko8q94bm6b6uo6gg35wwtp4k64p3p X-Rspam-User: Authentication-Results: imf11.hostedemail.com; dkim=pass header.d=google.com header.s=20210112 header.b=Ras6zX6z; spf=pass (imf11.hostedemail.com: domain of 3vCFoYgYKCLkfkhcdqfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--glider.bounces.google.com designates 209.85.221.74 as permitted sender) smtp.mailfrom=3vCFoYgYKCLkfkhcdqfnnfkd.bnlkhmtw-lljuZbj.nqf@flex--glider.bounces.google.com; dmarc=pass (policy=reject) header.from=google.com X-HE-Tag: 1650991546-609463 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: KMSAN does not instrument kernel/kcov.c for performance reasons (with CONFIG_KCOV=y virtually every place in the kernel invokes kcov instrumentation). Therefore the tool may miss writes from kcov.c that initialize memory. When CONFIG_DEBUG_LIST is enabled, list pointers from kernel/kcov.c are passed to instrumented helpers in lib/list_debug.c, resulting in false positives. To work around these reports, we unpoison the contents of area->list after initializing it. Signed-off-by: Alexander Potapenko --- Link: https://linux-review.googlesource.com/id/Ie17f2ee47a7af58f5cdf716d585ebf0769348a5a --- kernel/kcov.c | 7 +++++++ 1 file changed, 7 insertions(+) diff --git a/kernel/kcov.c b/kernel/kcov.c index b3732b2105930..9e38209a7e0a9 100644 --- a/kernel/kcov.c +++ b/kernel/kcov.c @@ -11,6 +11,7 @@ #include #include #include +#include #include #include #include @@ -152,6 +153,12 @@ static void kcov_remote_area_put(struct kcov_remote_area *area, INIT_LIST_HEAD(&area->list); area->size = size; list_add(&area->list, &kcov_remote_areas); + /* + * KMSAN doesn't instrument this file, so it may not know area->list + * is initialized. Unpoison it explicitly to avoid reports in + * kcov_remote_area_get(). + */ + kmsan_unpoison_memory(&area->list, sizeof(struct list_head)); } static notrace bool check_kcov_mode(enum kcov_mode needed_mode, struct task_struct *t)